stripped bolt holes in cylinder head?

[Graeham White]

I found out why my bike leaks oil. During Valve clearance setting today I found

both cylinder head covers have been stripped, all 4 bolts, both sides.

It is a large head bolt of small diameter, therefore overtightned previously, when it is not required, probably to crush older/dry seals. Ham fisted fleet mechanic?

 

Is my only options drill and helicoil? Anyone know the TPI? Experience with repair, mine can not be the first....no I did not do it.

 

G

 

p.s. found front end problem- lower ball joint nutt loose-

[upflying]

Actually it's the valve cover bolts that are stripped. The bolts only take light torque (8nm IIRC) or the bolts strip. Only way to repair is with a Helicoil or similar thread repair fix. I always use a clicking inch pound torque wrench when I secure my valve covers.

You are right, probably caused by a back yard hack using a Crescent wrench and plumbing tools to work on the bike.

[Graeham White]

OK

 

I will get new seals and bolts and have a go.

 

Cant hurt as step #1, fix the easy first.

 

thanks

 

G

[Don M]

Did the same to my RT a few years back and repaired it with a Time-Sert kit. Very easy to use and more positive than a Helicoil in my opinion. Never had a problem with the repair.

[Graeham White]

Do you remember the bolt size and pitch, possibly kit number for time-sert?

[John Dickens]

OK

 

I will get new seals and bolts and have a go.

 

Cant hurt as step #1, fix the easy first.

 

thanks

 

G

 

It's very rarely the bolts themselves which strip as they are steel.

 

It's normally the threads in the softer alloy cylinder head as you first suspected. The cure is to helicoil or similar.

[10ovr]

Do you remember the bolt size and pitch, possibly kit number for time-sert?

6x1.0 x9.4 I got my Time Sert kit through Wurth West Inc,1800 346 4198 Give them a call..

[Graeham White]

you guys are amazing. question=answer.

 

Do you predict lottery numbers?

 

it appears the rubber seal inside the head cover around bolt shank is same rubber as outside sealing face ( under washer) is that true?

 

G

[Dick_at_Lake_Tahoe_NV]

Another good source for the Repair Kit is NAPA. They carry a complete kit with about 8-10 inserts, a drill that is the correct size, a Tap, to tap the hole for the inserts, and the insert tool. Everything is easy to do and will take less than 1 hour per side.

[Joe Frickin' Friday]

you guys are amazing. question=answer.

 

Do you predict lottery numbers?

 

it appears the rubber seal inside the head cover around bolt shank is same rubber as outside sealing face ( under washer) is that true?

 

Yep. One single-piece rubber sealing grommet on each screw. Actually I've seen them break before; if you see two separate pieces on one screw, something's wrong.